1. Field of the Invention
The present invention relates to a shock-absorbing system for a shoe, and more particularly to a shock-absorbing system for a shoe, which has a compact structure and effectively absorbs and dissipates a shock imposed to a foot of a shoe wearer upon walk or exercise and rebounds an accumulated energy, whereby comfortableness and stability of the foot are simultaneously ensured.
2. Description of the Related Art
In our daily life, our shoes are the instruments that bear the weight of our body and are constantly subjected to the impact of that weight throughout the day. Our shoes are, therefore, the most important medium through which the external force acts on the body.
Accordingly, shoe manufacturers are seeking ways to provide a shoe that is stable and yet comfortable. Typically, stability of a shoe sole is enhanced by increasing its rigidity, and comfortableness is enhanced by increasing cushioning provided in a shoe. Thus, the more stable the shoe, the less cushioning that is provided, and conversely, the more cushioning that is provided, the less stable the shoe. As a result, stability is often sacrificed for the sake of comfortableness, and vice versa.
In this century, introduction of shoes designed specifically for athletic purposes has highlighted this problem. Many athletic activities involve running and jumping that translate to high impact forces on the foot. As a result, today's typical athletic shoe sole includes a cushion midsole layer that is sandwiched between the insole and outsole layers of the sole. This midsole layer is usually made of a foam material to provide maximum cushion effect to the foot.
However, the effect of using the midsole is much the same as providing an ordinary "kitchen sponge" in a pair of dress shoes, that is, only minimal impact absorption is provided. Moreover, the foam cushion material does little to stabilize the foot within the shoe. In particular, the foam cushion has no stability along the edge of the midsole, an area which without support can cause the foot to roll over upon impact with the ground (pronation and supination). Therefore, a balance between comfortableness and stability is essential in any performance athletic shoe.
As attempts to satisfy the requirements as described above needed in shoe, various methods, such as utilizing different density foam in select areas of a midsole, using a midsole having air cushion, etc. are disclosed in the art. One problem associated with the former is that the harder density foam is often so hard that it does not compress at all under the forces encountered during typical athletic activity, and other problem encountered in the latter is that the structure of shoe is complex and thereby the shoe becomes expensive while not perfectly satisfying the requirements.